When a vicious Youma attacks Tsukasa, a pink-clad kunoichi named Shizuri swoops in to save the ordinary salaryman. She says she’ll protect him from further attacks, but there’s a catch: Shizuri wants to move…

Follows male college student Kazushi Sudou and his childhood friends, the Shirakawa sisters. The story begins with strange circumstances, and the three of them end up bathing together.